The last couple weeks, which is I guess just the last couple times I've driven the truck, it's been starting to run a bit rough. And went from around 13-14 mpg to 8 mpg.
I got myself stuck completely flexed out for about a half hour a couple weeks ago up in the woods alone. Hilift jack to the rescue. But the flex actually pulled my airhose off the box which I didn't find out about until I got home. Thought it explained the problem and seemed to work fine once I fixed it. Then back out in the woods again I found the diverter behind the grill covering the opening for the intake, wired it back into place. But it still ran rough off and on for the drive home.
Today I finally have time to do some work on it. I pulled a plug and this is what I found.

The wires don't look bad, but they don't look that great either.
Picked up some plugs, wires, fuel filter, and battery terminals. Terminals keep corroding and one is cracked.

I will be replacing the air box and all, but I need to put in my efan, take out the old one (clutch stuck), and put in a longer radiator hose so that the k&n will fit. Hopefully next weekend I'll get to that.

Would the intake problems have caused the plugs to do that? They reek of unburned gas. Or could there be something else as well?

 

The thread color is really of concern, the electrode is what tell the story. It looks black, so carbon build up or oil fouling I cant tell.

These plugs look like they have some miles on them.

My advice is plugs, wires, and upstream O2's.

Rough idle can be a vacuum leak. Especially if it runs well once you push the skinny pedal.

 

Those plugs look like the engine was running really rich. Could have been when the intake became unplugged and the PCM wasn't able to monitor the amount of air coming in and control the air fuel ratio.

 

plugs, wires and battery terminals done. only had time to run it for 5 minutes or so but it was running great. Going to be a few days before I have time for much else.